Has anybody done this? When does the factory intake manifold and throttle body begin to choke off the engines potential? I know a new flange would have to be welded on but would the tps and coolant lines hook up as well. How well are the factory 4age intake manifolds designed...is there a lot of improvements that could be made by getting a custom one made? (better flow, velocity stacks, larger plenum)?? Also everybody always talks about how the large port 4age has too low of intake velocity due to the size of the ports...could this be changed by mating a small port intake manifold to a large port head??
I did the same thing to my mk1 mr2 and put down 118whp on stock cams. Ive got a 7mge throttle body that Im planning on adapting to fit to to the smallport intake manifold in the near future.
The largeport has port the size of the 4g63 if not bigger (2.0l engine!) so there are definitely gains to be made by swapping heads. I noticed the largest increase off idle and at part throttle, but there are still large gains everywhere else as well.
I havent looked into how the 7mge cold idle works so I really have no clue what to do. I also noticed that there is a 2nd linkage that opens up when the throttle is opened that I have no clue what is for. When I find time to make an adapter I may just block off every port on the TB and loop the coolant lines to eliminate the cold start. Damn things been giving me enough problems as is.
What about if Ive already gotten a lot of head work done and if small port heads are hard to find. Would switching to a small port intake manifold on a large port head and eliminating the tvis make any difference. Or getting a whole new mainfold built. Nozzs intakes will build a custom intake for 450.... not too bad as Ive seen custom intakes go for more around double that cost. The specs of what Ive done to my engine are fairly similar to Oldshooltoy, but not near as detailed. I have a large port head, 10.3:1 pistons and right away ill be putting in my WEB 577s
There have been a few mr2 owners that have commented on a noticeable increase by just running the smallport intake manifold on the bigport head. Tho honestly I would keep searching for a smallport head. Mr2 owners seem to stockpile parts, so its not hard to find someone with a blown smallport 4agze with a good head.
I would never pay 450 for a custom intake manifold that wasnt dyno proven. I payed 150 for a complete smallport head, intake manifold and fuel rail.
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